"Two-Electrode Biopotential Measurements: Power Line Interference Analysis"

E. SPINELLI; M. MAYOSKY

IEEE TRANSACTIONS ON BIO-MEDICAL ENGINEERING

IEEE

Lugar: New York; Año: 2005 vol. 52 p. 1436 - 1442

0018-9294

Abstract—In this paper, an analysis of power line interference in two-electrode biopotential measurement amplifiers is presented. A model of the amplifier that includes its input stage and takes into account the effects of the common mode input impedance ZC is proposed. This approach is valid for high ZC values, and also for some recently proposed low-ZC strategies. It is shown that power line interference rejection becomes minimal for extreme ZC values (null or infinite), depending on the electrode-skin impedance’s unbalance
ZE. For low
ZE values, minimal interference is achieved by a low ZC strategy (ZC = 0), while for high
ZE values a very high ZC is required. A critical
ZE is defined to select the best choice, as a function of the amplifier’s Common Mode Rejection Ratio (CMRR) and stray coupling capacitances. Conclusions are verified experimentally using a biopotential amplifier specially designed for this test.